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Why Does My Coffee Smell Like Cat Pee?

Will Beck
Last Updated: February 28th, 2023

Have you ever encountered a cup of freshly brewed coffee with a pungent odor like urine? If so, you probably asked yourself, “Why does my coffee smell like cat pee?”.

There are various reasons that can explain why your coffee smells like cat pee. But, the most common reason is because of spoiled coffee beans. If your beans release oil that becomes rancid, it can affect your coffee’s overall taste and smell.

And yes, the smell would be like that of a cat’s urine.

However, this isn’t the only reason why this happens. In this blog, let’s dig deeper into all the other reasons why your coffee smells like cat pee. Let’s get started.

Why Your Ground Coffee Smells Like Cat Urine

ground coffee smells like cat urine

The major reasons why your coffee smells like cat urine are

  1. Improper roasting and brewing
  2. Improper storage
  3. Poor packaging
  4. A low-quality coffee brand
  5. Moist coffee beans
  6. Dirty brewing systems

However, it’s a little more detailed than just that. Let’s take a deep look at how these two things affect the way your coffee smells.

Improper Roasting and Brewing

improve coffee roasting

Coffee should have a flavourful and pleasant aroma. Bu,t during the roasting process, it tends to create less aromatic oils. This happens especially in high-temperature conditions.

The oils can smell like cat pee, especially when the process involves improper procedures. This happens when the proper roasting protocol is not followed, affecting your coffee’s smell.

Aside from the roasting process, the brewing method can also affect and alter your coffee’s flavour and smell notes. But, it’s uncommon that it would smell like a cat’s pee just due to brewing alone.

Improper Storage

improper storage

Improper storage of your coffee grounds can also lead to a weird smell. The coffee beans can be overexposed to oxygen when stored in open containers.

This leads to oxidative reactions because of the antioxidants present in your beans. When this happens, your ground coffee develops a high-acid taste and a cat pee smell.

Poor Coffee Packaging

poor coffee packaging

Sometimes the reason why coffee smells like cat pee has something to do with your coffee packaging. If you smell cat urine in your coffee, check to see whether the packaging has been damaged.

When your coffee packaging is damaged, it lets oxygen get in. This links back to the same problem with improper storage; the beans oxidize and develop a sour taste and foul smell.

You should also check the expiry date and see whether your coffee’s already expired. If you find out it’s way past the expiry date, you need to replace these beans and dispose of them immediately.

The Coffee Brand Might Be Cheap

If your coffee is a cheap brand, consider replacing it with more premium quality beans. Cheap coffee brands tend to go off faster than premium ones.

When they go off, the beans create an ammonia-like smell similar to the aroma of cat pee. If your coffee is going off quickly all the time, it might not be a bad idea to upgrade your coffee beans.

Your Coffee Beans Might Have Excess Moisture

Sometimes, your coffee beans get wet. This usually happens when you use a wet spoon to scoop coffee beans when making your cup.

Excess moisture damages your beans and makes them go moldy. The moisture can also spoil your coffee quicker, leading to a foul smell.

You Don’t Clean Your Coffee Pots and Mugs Regularly

clean your coffee pots and mugs

You must always clean your coffee pots and mugs using a dishwasher or warm water and soap. When coffee residue is left in your pots and utensils, they become hard to clean, even with decent washing.

Failing to clean your coffee pots can lead to bacterial growth. The bacterial growth can contaminate your coffee and lead to nasty smells.

White vinegar and salt combination is one of the easy hacks for cleaning coffee stains. Or, just pop your coffee utensils in the dishwasher and you can get rid of these scents.

What Can You Do To Avoid A Cat Pee Smell In Your Coffee

to avoid cat pee smell in your coffee

How you store your coffee greatly affects how it lasts, the smell, and even the taste. Placing your beans in a tightly sealed container is the best way to keep them fresh.

You should also make sure that the container is completely dry before pouring your beans into it. Remember that excess moisture can affect your coffee’s smell. Before brewing your coffee, take it out of the container and let it breathe.

Don’t forget that the coffee beans themselves should be completely dry too! The moisture from these beans can also contribute to your cup having a weird smell after brewing it.

Another way to conserve the freshness of your coffee is by placing your beans in opaque containers. These containers are safe from heat and light, protecting your beans.

Not freezing your coffee beans can also help retain their flavor. So the best way to store them is in a cool and dry place at room temperature.

Coffee Smell Like Cat Pee – FAQ

Do you still have a couple of questions about why your coffee smells like cat pee?

I understand. Here’s a quick FAQ to help you clear up any lingering questions you might have.

Why Does My Coffee Smell Like Tuna, or Is It Fishy?

A few reasons why your coffee smells like fishy is because oxidation occurred during storage or because the beans weren’t stored right after roasting. Alternatively, the equipment and storage container could be dirty.

Why Does My Coffee Smell Like Poop?

A possible and common reason why your coffee smells like poop is that the coffee beans were over-roasted. Over-roasting the beans can lead to your coffee having a strong aroma.

Aside from the strong aroma, the beans can also produce an oily liquid with a thick consistency. And, when you try to make a cup, the taste becomes very bitter with burnt notes. This flavour profile can be responsible for your coffee smelling (and tasting!) like poop.

Another reason is because of the elements of your coffee grounds. They contain magnesium, potassium, and other minerals. Because of these substances, coffee beans produce a poop-like smell when over-roasted.

What Happens When Coffee Smells Like Ammonia?

When your coffee smells like ammonia, it’s a possible sign that your beans are not properly stored. The ammonia smell is usually because of excess moisture in your coffee beans.

The only way you can fix this problem is by transferring your coffee beans to better storage. You should also make sure your coffee maker is fully dried before brewing a cup of Joe.

How to Know Whether Your Coffee Is Rancid?

You can tell if coffee is rancid through its smell and taste. Rancid coffee will smell flat, dusty, or mildewy. It’s also easy to tell when coffee is old because it smells like an ashtray.

When it comes to taste, bad coffee will taste anything from dull to sour. Because it can be hard to tell whether you should be replacing your coffee, there is a hack you can do.

Make a cup and leave it for at least 1 hour, then have a sip. If the taste is anything sour and bitter, it’s most likely time to replace your beans.

Can You Still Do Something With Expired Coffee?

Yes, you can recycle your coffee beans even after their expiration date. As long as they are not too far off, use your coffee beans in the following ways:

  • Baking – in brownies, tiramisu, and syrups
  • Gardening – use ground coffee as a fertilizer
  • Insecticide – insects hate coffee
  • Exfoliation – you can mix it with coconut oil, creating a body scrub

Always Make Sure Your Coffee is Fresh

fresh coffee beans

Fresh coffee is what we all want. And, if it starts to smell like cat pee or give off other weird aromas, check your beans to ensure that they’re not old, moldy, or stale.

Always make sure your coffee beans are in tightly sealed containers and kept out of moisture. And, remember to clean your coffee makers, pots, and containers.

This prevents contamination that could urine your coffee’s flavour and aroma and helps you have an enjoyable beverage for the weeks and months to come!

Further Reading

About The Author

Will Beck

Will is a true digital nomad, taking his work on the road at every opportunity. His first love is coffee, with whiskey a close 2nd. He loves nothing more than enjoying a perfectly brewed coffee with spectacular scenery whilst he coordinates behind the scenes of the Drink Stack blog!

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